Biostatistical Core will provide biostatistical support to the project investigators. Editorial, study design and biostatistical support will be provided. The investigators in the project are colleagues who have worked together as a group for up to 15 years and on oral AIDS research for up to 10 years. The Cores and Projects are well defined and are led by PI's who identify strongly with their own components. Though each component will have its own budget, there will be a great deal of collaboration and interaction between the components, which share common concepts and goals. These interactions, and the initiatives which will grow out of them, will be guided and coordinated by the Biostatistical Core.